Question

An automobile travels on a straight road for 42 km at 46 km/h. It then continues in the same direction for another 42 km at 92 km/h. (a) What is the average velocity of the car during this 84 km trip?(b) What is its average speed in m/s?

Answer 1

Answer:

(a) Average velocity is 61.356 km/hr

(B) Speed in m/sec will be 17.04 m/sec

Explanation:

We have given  that automobile traveled 42 km of the distance with a velocity of 46 km /hr

So time taken by automobile to cover 42 km with velocity of 46 km/hr

Time $t=\frac{distance}{speed}=\frac{42}{46}=0.9130hour$

Now for other 42 km velocity of automobile is 92 km/hr

So time taken for this 42 km $t=\frac{distance}{speed}=\frac{42}{82}=0.456hour$

So total time = 0.913+0.456 = 1.369 hour

Total distance = 42+42 = 84 km

So average velocity $v=\frac{distance}{time}=\frac{84}{1.369}=61.356km/hr$

(b) Now we know that 1 km = 1000 m

And 1 hour = 3600 sec

So $61.356km/hr=61.356\times \frac{1000m}{3600sec}=17.04m/sec$